(1) Field of the Invention
The invention is related to an actuator, especially for seat adjusting devices having at least one electric motor with a subordinate reduction gear and a disconnecting device for manual operation.
(2) Description of the Related Art
Electrical actuators are for comfort or adjustment of inaccessible adjusting links. In case of a voltage failure or other such defects, it should be possible to adjust the links manually; this is normally the case with seat elements too. As actuators usually have high-reduction, partly self-locking reduction gears, a manual adjustment to create the required torque is possible only with the help of a coupling between the electric motor and the reduction gear or within the reduction gear.
An actuator for seat adjustment devices is known from DE-OS 102 30 591, in which the drive path between an electric motor and an output means of the actuator can be interrupted manually, where a traction rope transfers the force of a manually activated lever to a disconnecting device, which blocks the gear ring of a planetary gear against rotation during the operation of the electric motor, but allows rotation in the manual mode.
FIG. 1 shows parts of an actuator 1 according to the state of the prior art, with a planetary gear 9 consisting of a sun gear 20 attached to a shaft 22, planet gears 21 that are mounted on a planet carrier (not shown) and a gear ring 5 that is simultaneously an integral part of a disconnecting device 4. The gear ring 5 has a coupling means 7 formed from a ring 17 on its peripheral side 6 as cutouts in which the counter-coupling means 8 intervenes on being impacted by a spring. The coupling means 7, 8 are mutually coordinated in such a way that a clearance-free coupling connection results in the coupled condition. The counter-coupling means 8 is a part of a swivel device 23 consisting of a coupling shaft 18, the ends of which are either integrated into one piece, or connected permanently to a traction lever 11 on one side and a counter-coupling means 8 on the other side. Together with one of these rotary bearings fixed to the housing, the coupling shaft 18 forms a swivel joint 15, where the swivel device 23 consisting of a coupling shaft 18, traction lever 11 and counter-coupling means 8 can swivel around a swivel axis 19. The coupling shaft 18 has a supporting means 24 facing the counter-coupling means 8 which is impacted by a coupling insertion spring 12 guided to an expansion mandrel 13 in such a way that the gear ring 5 of the planetary gear 9 is locked against rotation in the normal operation mode. The expansion mandrel 13 has a set base 14 that supports the coupling insertion spring 12 as a compression spring. The disconnecting device 4 can be disengaged manually over a Bowden control cable 10 (only indicated here).
FIG. 2 illustrates an actuator 1 according to the state of the prior art, having a housing 16 (displayed as opened) in which the following items are arranged: planetary gear 9 with the sun gear, planet gears, a planet carrier 25 and the gear ring 5, the coupling means 7 arranged on the peripheral side of the gear ring as a first component of the disconnecting device 4, the swivel device 23 consisting of the counter-coupling means 8, the coupling shaft 18 that is mounted in the housing 16 and the traction lever 11 that is in active connection with the Bowden control cable 10.
The Bowden control cable 10 that is held in place by a support 26 impacts the traction lever 11 and swivels the coupling shaft in the process and therefore, also the counter-coupling means 8 against the force of the coupling insertion spring 12 from the coupling means 7. To achieve zero clearance, coupling means 7 and counter-coupling means can be designed in the shape of a trapezium, so that the spring force of the coupling insertion spring 12 always takes care of adjacent coupling surfaces.
With the Bowden control cable not activated, the compression spring 12 holds the counter locking means 8 in its grip without any clearance with one of the latching means 7 and ensures that the gear ring 5 is quasi attached to the drive housing. This enables the operation of a customary actuator consisting of an electric motor and a reduction gear for setting an adjusting unit, e.g., a seat element, where the sun gear 20 drives the planet gears 21 interlocked with the gear ring 5 and therefore, the planet carrier that functions as the output of this gear level of the actuator. If the Bowden control cable is activated, the traction lever 11 swivels, and the counter-coupling means 8 connected via the coupling shaft 18 with the traction lever 11 around the swivel axis 19, where the counter-coupling means swivels away laterally from the coupling means 7. The swivel movement displaces the expansion mandrel 13 in its axial direction by the supporting means 24, which presses the compression spring 12 over the base 14, stretching it, so that an insertion movement of the counter coupling means with the Bowden control cable released takes place automatically. If necessary, the gear ring is locked only after activating the electric motor, as soon as the counter-coupling means 8 is brought in agreement with one of the coupling means 7.
In the disconnected condition, the gear ring 5 can be rotated freely in the housing. A reverse counter force from the adjusting unit can no longer be accepted by the gear ring 5 in this condition, hence the planet gears 21 roll during manual activation of the adjusting unit (e.g., seat element) and the planet carrier driven by it on the sun gear, and carry the gear ring along. The Bowden control cable enables or simplifies manual activation.
The known disconnecting device covers a single reset spring which tries to maintain the engaged position of the disconnecting device on the one hand, and resets the manually operated lever on the other hand. As such disconnecting devices are not designed for a single application for economical reasons, and it must be possible to adapt them to a large number of installation geometries, the disconnecting device must be designed to withstand all expected forces. Traction ropes have the unique property that the rope length protruding from a rope supporting system changes according to the number and amount of bending angles in the rope course. This longitudinal change leads to a partial disengagement of the disconnecting device so that under unfavorable conditions, the gear ring can be released without activating the manually operated lever, while it remains securely locked in other installation geometries. Moreover, the friction ratios of the traction rope can be influenced by different bending angles so that the insertion force which feeds the reset spring is not adequate in each and every case to ensure a safe insertion of the disconnecting device. In applications in which the traction rope of the Bowden control cable follows the movement of the adjustment, this factor can lead to situations in which the coupling disengages. This would make the actuator ineffective.
Hence, the task of the present invention is to provide a generic actuator with a disconnecting device that can be used for a large number of different applications and installation conditions and that guarantees a reliable function of the coupling device in all processes and methods without being over-dimensioned and therefore uneconomical.